PB1720: STUDY ON THE MECHANISM OF ZHIGANCAO DECOCTION REGULATING MIRNA-21/ TLR4/ MAPK PATHWAY TO IMPROVE DOXORUBICIN-INDUCED MYOCARDIAL APOPTOSIS
Authors: Suzhen LI, Xing Cui
Journal: HemaSphere (2023)

Topic: 1. Acute lymphoblastic leukemia - Biology & Translational Research Background: Doxorubicin (DOX) is a chemotherapeutic drug widely used in the treatment of leukemia. However, DOX-induced cardiomyocyte apoptosis in leukemia patients is an important clinical problem. DOX-induced cardiomyocyte apoptosis is related to oxidative stress, inflammatory response, autophagy and other pathways. Clinical studies have shown that high expression of Toll-like receptor 4 (TLR4) can be used as a genetic marker of early diastolic dysfunction in DOX-induced cardiomyopathy.And miRNA-21 can target TLR4,Overexpression of miRNA-21 can inhibit TLR4 expression to reduce cardiomyocyte apoptosis and inflammatory response in myocardial ischemia-reperfusion injury, suggesting that DOX-induced cardiac function damage can be reduced by regulating miRNA-21/TLR4 pathway. Zhigancao Decoction (ZGCT) is a traditional Chinese medicine prescription. Studies have reported that ZGCT can improve cardiac structure and function, reduce creatine kinase (CK) and lactate dehydrogenase (LDH) activity, and effectively prevent DOX-induced cardiotoxicity. However, the specific protective mechanism of ZGCT on DOX-induced cardiomyocyte apoptosis is still unclear. Aims: To explore the potential mechanism of Zhigancao decoction in the treatment of doxorubicin-induced myocardial injury. Methods: Myocardial apoptosis cell model was constructed in H9C2 cells induced by DOX and were co-commulated with FBS, differernt dose of zgct,respectively.Mouse model of myocardial injury induced by DOX was constructed and intervened with normal saline, ZGCT and miRNA-21 antagomir.CCK-8 was used to detect the viability of H9C2 cells. TUNEL assay was used to evaluate cardiomyocyte apoptosis. ELISA was used to evaluate the levels of myocardial injury markers LDH and CK. The expression levels of miRNA21 and TLR4 were detected by qPCR. The double luciferase report further clarified the evidence that miRNA-21 targeted TLR4. The expression levels of TLR4, MAPK and Casp3 in oxidative stress and apoptosis were detected by immunohistochemistry. Hematoxylin-eosin (HE) staining was used to observe histopathological changes. Results: In vitro experiments showed that miR-21 was significantly down-regulated in DOX-induced myocardial injury group. After overexpression of miR-21, the viability of H9C2 cells induced by DOX was significantly improved (A), and the expression levels of LDH and CK, markers of myocardial injury, were significantly decreased (B). The results of PCR showed that miR-21 expression was down-regulated and TLR4 expression was up-regulated in DOX-induced myocardial apoptosis;Luciferase showed that miR-21 directly targets TLR4(C). Network pharmacology predicts that ZGCT can regulate apoptosis and oxidative stress to improve myocardial injury(D-E). In vitro experiments further proved that ZGCT can improve myocardial cell viability, down-regulate apoptosis and oxidative stress levels(F-H). In vivo experiments confirmed that Zhigancao Decoction can significantly down-regulate the expression levels of myocardial injury markers LDH and CK, and inhibit TLR4/ MAPK/ Casp3-mediated myocardial apoptosis(I-K). Summary/Conclusion: In summary, Zhigancao Decoction, a traditional Chinese medicine preparation, improves doxorubicin-induced myocardial apoptosis by modulating proinflammatory cytokines expression via the miRNA-21/ TLR4/ MAPK pathway.Keywords: Chemotherapy, Doxorubicin, Chemotherapy toxicity, Anthracycline